Magneto



Jan. 2, 1934.

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MAGNETO Filed July 22. 1930 3 Sheets-Sheet 3 Zmventor Uar'i F ,Rez'a zif(I ttorneg-r" Patented Jan. 2, 1934 1,942,123 MAGNETO Curt Rois,Chicago, Ill., .assignor to Excel Magneto (30., Chicago, Ill.

Application July 22, 1930. Serial No. 469,882

' 1 Claim.

My invention relates to magnetos and particularly to an improved magnetoof extreme simplicity, which will be strong and durable and can bemanufactured at a minimum cost.

One object of my invention is to provide a magneto in which the magnetsmay be replaced without dismantling the working parts.

A further object is to provide a magneto wherein the field strength maybe changed to agree with varying conditions of use, but without 2.1-teration of the fundamental structure.

Still another object is to provide a new form of magnet which does notrequire annealing, and,

hence will maintain higher residual magnetism and coercive force thanother forms -of magnet at present in use.

Other objects will appear from the following description when read inconjunction with the accompanying drawings wherein: 1

Figure 1 is a perspective view of one form of magneto embodying myinvention, parts being broken away to show the interior construction.

Figure 2 is a horizontal sectional view of the complete magneto.

Figure 3 is a perspective View of the rotor.

Figure 4 is a top view of one form of field piece suitable for use in myimproved magneto, a pair of these field pieces being shown in assembledrelation with a magnet.

Figure 5 is a section on line 5--5 of Fig. 2, showing a breakerconstruction adapted for use when an adjustable spark is desired.

Figure 6 is a perspective view of one of the pole pieces shown in Fig.4, illustrating the contour of the polar extensions.

Figure 7 is a perspective view of one of the improved magnets.

Figures 8 and 9 are vertical sectional views, transverse to and parallelto the rotor shaft respectively, both being illustrations of a form ofbreaker construction adapted for use when a fixed spark is desired.

Similar reference characters. refer to similar parts in each of theseveral views.

Referring to Fig. 1, reference character 10 designates a housing of castnon-magnetic material, such as aluminum, in which are embedded magneticpole pieces 11, of high permeability iron or of commercial steellaminations. These pole pieces have integral polar extensions 16, cutaway at 17 to embrace the rotor of the magneto. Housing 10 is initiallyconstructed by placing pole pieces 11 and the rotor mounted in its bearings in proper relation in a mold and then pourj ing in the moltennon-magnetic material. When the mold is filled to the proper depth, andthe cast material has hardened, the moldsections are removed, leavingthe housing 10 in the form shown. The pole pieces will he rigidly heldin properly spaced relation with the flat .end, faces 11a flush with theouter faceof the housing.

The end of housing 10, where pole piece ends 11a are exposed, is .flatand adapted to receive one ormore flat-permanent magnets 12 havingcentral opening-s13, through which the rotor 65 shaft extends. Thesemagnets are simple punchings of steel, cut to the required lengthwithout heat treatment. .Since they are not annealed they will retaintheir magnetism for a long period and will possess very .high coercive 7force. They may be of chrome, tungsten or cobaltsteel and are secured tohousing .10 by any suitable means, such as screws 15, passing throughopenings 14 in the magnets. It will be obvious that the first magnetapplied to the hous- 7 ing contact with the ends, 11a of the pole piecesas shown in detail in Fig. 4. Any desired field strength may be securedby increasing or decreasing the number of magnets 12, which areemployed. 89

The housing has an open top, through which a generating coil 18 can beinserted for cooperation with pole pieces 11. This coil is carried on alaminated magnetic core 19, having stepped ends which hold the core inbridging relation to the pole pieces 11, the core being secured to thepole pieces by the same screws 27, which secure the magneto cover 26 inplace (Fig. 8).

The housing 10 has embedded in its ends, bearings 24 and 25 of anysuitable material, such as bronze, carrying a rotor on shaft 21. Thisshaft is enlarged at 20 to receive the cylindrical rotor, the projectingend of enlargement 20 abutting the bearing 24 to limit end play. Therotor is composed of non-magnetic material 23 cast in place about theenlargement 20, and having embedded in it two sets of magneticlaminations 22. These sets of laminations are placed on diametricallyopposite sides of the rotor and are of such angular extent as to becapable of bridging the polar extensions 16, when the rotor ismovedthrough 90 degrees from the position shown in Fig. 1, and of ahorizontal length equal to that of polar extensions 16, as clearly shown1 5 in Fig. 2.

It is quite usual to provide magnetos of this character with anadjustable circuit breaker and I have shown in Figures 2 and 5, one formof breaker which can be simply constructed, but 1 1p which will besatisfactory and durable in operation.

In order to provide for this breaker, a hollow end cap 28, of insulatingmaterial is adjustably mounted on the end of housing 10 adjacent torotor 23, this adjustment being permitted by two spaced circumferentialslots 29 cooperating with screws 30. Any suitable adjusting connection,such as a short arm may be applied to this cap. The stationary breakercontact 31 is mounted on an arm 32 having an arcuate extension 33permanently secured to cap 28 as by rivets 34. In similar manner thecooperating movable contact 35 is carried by a long spring arm 36,having an arcuate extension 37 secured to the cap by rivets 38. Themovable contact is operated by a cam 39 secured to the end of rotorshaft 21 by a pin 40. I prefer to make this cam 39 of stamped compressedlinen treated with a suitable varnish of phenolic condensation product,as cams of this material are far superior to steel because they do notexpand or contract with changes in temperature and require nolubrication. In assembling the breaker, arm 36 is provided with aninitial set which biases it downward so as to insure that the contacts35 and 31 will close when cam 39 rotates through ninety degrees from theposition shown. Both of the contacts are adjustable in the usual manner,as shown in Fig. 5, and are bridged by a condenser 41, mounted inside ofcap 28.

If a fixed breaker arrangement is desired, the construction of Figures 8and 9 may be adopted. In this modification the breaker is operated bydirect engagement with earns 42 embedded in the material 23 of therotor. Provision for this is made by having openings 43 and 44 in polepieces 11 and housing 10 adjacent thereto, the contact arms beingsecured to the housing by bolts and nuts 45.

When the rotor is set in rotation by any suitable means, the laminations22 bridge the polar extensions 16 twice during each revolution, therebyproviding a parallel shunt path for the flux which normally passes fromthese polar extensions through core 19 of coil 18, these extensions inturn receiving the flux from magnets 12. Flux, therefore, passesalternately through laminations 22 and core 19 to cause a pulsating fluxto cut the turns of coil 18 and set up a flow of current therein. Thiscurrent may be conducted away from coil 18 in any well known manner.

The magneto herein shown and described is designed to be eflicient anddurable, and yet capa ble of manufacture for a very small sum. It hasthe advantages of few parts, permanent integral assembly, variable fieldstrength and complete enclosure, whereby, dirt and moisture arecompletely excluded. While I have illustrated a bipolar assembly, it isobvious, that my invention is applicable to magnetos having more thantwo poles.

Although I have herein shown and described only one form of magnetoembodying my inven tion, it will be obvious that changes may be made inthe details, within the scope of the appended claim, without departingfrom the spirit and scope of my invention.

Having thus described my invention what I claim is:

A magneto comprising a plurality of pole pieces embedded in a housing ofcast non-magnetic material, with their ends exposed; a rotor within saidhousing between said pole pieces; a plurality of flat permanent magnetsremovably mounted in magnetic relation to the exposed ends of the polepieces and threaded over the rotor shaft; and a generating coilmagnetically associated with said pole pieces and rotor CURT F. REIS.

